Deep diode varactors

Claim 1

A semiconductor varactor comprising a body of semiconductor material having two opposed major surfaces forming respectively the top and bottom surfaces of the body, a predetermined level of resistivity, a predetermined first type conductivity, a preferred crystal structure and a vertical axis substantially perpendicular to the major opposed surfaces; at least one of the opposed major surfaces having a predetermined crystal planar orientation which is one selected from the group consisting of (100), (110) and (111); a plurality of spaced planar regions of recrystallized semiconductor material of the body having a second and opposite type conductivity than that of the body and a predetermined level of resistivity formed in the body and so oriented as to be aligned with a first preferred crystal axis of the material of the body; each of the spaced planar regions having two opposed major surfaces extending between, and terminating in, the opposed major surfaces extending betweeen, and terminating, in, the opposed major surfaces of the body and oriented substantially perpendicular thereto and substantially parallel with the vertical axis of the body and a second preferred crystal axis of the material of the body; the recrystallized material is formed in situ by the migration of a melt of metal-rich semiconductor material of the body by thermal gradient zone melting at a predetermined elevated temperature along a thermal gradient substantially parallel with the second preferred crystal axis and the vertical axis of the body and has a predetermined level of concentration of the metal of the melt as determined by the solid solubility limit of that metal in that semiconductor material at that predetermined elevated temperature of migration and the metal is distributed substantially uniformly throughout the entire region; the metal consisting of at least one dopant impurity material to impart the type conductivity and level of resistivity to the planar region; a P-N junction formed by the abutting, contiguous surfaces of the material of each of the planar regions and the material of the body; each P-N junction being substantially perpendicular to, and exposed at, the major opposed surfaces of the body; the spaced planar regions and the material of the body between each pair of planar regions defining a lamellar structure of a plurality of integral diodes arranged in a series electrical circuit; electrical contact means affixed to selected surface areas of the body to enable a predetermined number of P-N junctions to be biased by an applied potential; and the electrical characteristic of the varactor is a voltage dependent capacitance.